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Bentley GT P0171 safe to drive?

Old Nov 10, 2019 | 09:06 AM
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Bentley GT P0171 safe to drive?

Shortly after picking up my 2007 Bentley GTC, it threw a P0171 error. Spoke to a Bentley dealer and they advised that it can happen after refuelling.Especially since the car had not been driven much recently (it had done about 350 miles in the year prior to my purchase and was stored in a garage).
I reset the ECU and the code stayed away for 200 miles or so but has come up again. The car seems to be running fine. Just done am 8 hour trip from Kent to Scotland and averaged 24 mpg. Smooth idle, no hesitations.

Is it safe to keep driving the car with this error before I get it properly checked back home? I still need to drive 800 miles or so back from Scotland to home.
 
Old Nov 10, 2019 | 09:27 AM
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if u can post your Long Term fuel trim here then we can give u an answer... normally lean code is bad for engine
 
Old Nov 10, 2019 | 09:35 AM
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Originally Posted by nguyennhatquang
if u can post your Long Term fuel trim here then we can give u an answer... normally lean code is bad for engine
How do I get that? I only have a basic OBS2 reader.
 
Old Nov 10, 2019 | 03:51 PM
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Originally Posted by nguyennhatquang
if u can post your Long Term fuel trim here then we can give u an answer... normally lean code is bad for engine
This is good advice from NG. Fuel trims can give you good information that can help pinpoint a lean fuel condition, and as NG said lean is not good, Rich which is not that good either is at least less destructive. All OBD II systems are set up to light a CEL once lean conditions reach 25% correction. Past that the ECU can no longer correct LTFTs for more than 25% lean. Lean conditions cause extra cylinder heat, to extreme heat which can kill an engine quickly if bad enough.

Forget the laundry list of possibilities for lean conditions that come up with a google of P0171. Instead, and on this engine focus first on air leaks. That starts from the MAF sensors (one one each side) then continues on through the induction tubes, through the intercoolers, then into the throttle bodies and finally into the intake manifold. On this particular engine layout, there are miles of "plumbing" that include metal, plastic and rubber parts. Air leaks past the MAF measurement is the more likely cause.If everything is in tact there, then come back to us because we can then go deeper. Otherwise, you'll be all over the place and checking everything on a google search can be expensive and time consuming.

Also, skip any notions of fuel mixture issues. fueling is controlled in an algorithm that uses O2 sensor input, MAF input, IAT input, speed density tables. This is not like the days of carburetors. Fuel mixture choice is purely fixed with fuel injectors. These are not going to be your issue either, otherwise, you'd be getting a different set of fault codes.

In short, fastest (easiest) possibility is look for air leaks. if there is integrity there, then we can go to the next level.

Keep us posted where you go and what you do.

One last point - OP, you asked about fuel trims. You need a data logger to capture FTs. there are a number of devices out there that can. Your scan tool MIGHT. Some do based on the model. But, without a datalogger, you cannot.
 

Last edited by BWings; Nov 10, 2019 at 04:14 PM.
Old Nov 10, 2019 | 04:29 PM
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Thanks for the answers guys!
But, from what if can gather from the various replies in most cases it could be a faulty “thing”, eg faulty MAF sensor. Which, considering the engine is running fine, is what I think is happening in my case. So correct me if I’m wrong but if the MAF sensor is wrong and triggers the ECU to overcompensate, it causes the fault, no? Ie it’s a sensor problem and not an engine problem?
 
Old Nov 10, 2019 | 04:39 PM
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Originally Posted by kongolo
Thanks for the answers guys!
But, from what if can gather from the various replies in most cases it could be a faulty “thing”, eg faulty MAF sensor. Which, considering the engine is running fine, is what I think is happening in my case. So correct me if I’m wrong but if the MAF sensor is wrong and triggers the ECU to overcompensate, it causes the fault, no? Ie it’s a sensor problem and not an engine problem?
On a LEAN condition (because it is so serious and can be so damaging to the engine) the EMS limits the amount of adjustment the ECU is allowed to do to 25%. Once the ECU has adjusted over fueling by 25%, the CEL is set and the ECU then moves to and uses a fixed fueling table (which is pig rich).

Bottom line, you need to find and correct the cause of the lean condition. A P0171 is a global lean condition. It is distinguished from individual cylinder problems which would have different codes. In other words, the P0171 is telling you that at some place AFTER air volume has been determined, less air than that actually reached the cylinders. So the fueling the ECU determines is getting corrected by what is actually burned and showing up at the front O2 sensors.

On this engine, the MOST likely cause is an air leak past the MAF
Then, if there are no air leaks, start questioning the sensors. More likely on this engine to be the MAF, but could be the O2 sensors. Or (and PLEASE seek NGs help here) a wiring issue to the sensors (common as the MYs get older).
 

Last edited by BWings; Nov 10, 2019 at 04:42 PM.
Old Nov 10, 2019 | 05:33 PM
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Originally Posted by W12-All.The .Way
ive read a lot of these post the last couple of days bwings you have a problem with rico read that other blog and this one these petty digs you keep given out to rico so childish
theres nothing wrong with ricos answer the points he made are correct infact you have used the same info and added a few more lines on ricos just list of faults that can occur with code p0171
one issue stops and another developes you and one other still on at him what is it you dont like about this man what is it that makes your blood boil that hate you have one only has to read between the lines to see that
i cant just sit back and see this hsppen time after time its like a vendetta
i hope he doesnt come on and see what youve done again and responds "be the bigger man rico" and leave these petty people to there devices carry on with the good work and the time and devotion you put into this forum

This post is un called for. A few of us know who you are W12, so you can stop this BS. No one made you thread police. You have no business here unless you can help the OP. Quit the game Rico. We know who you are!
 
Old Nov 11, 2019 | 06:35 AM
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@kongolo VCDS is the easiest way... u can swap MAF from side to side..
 
Old Nov 11, 2019 | 07:44 AM
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Originally Posted by Rico.Adams
For the love of god stop this nonsense.

W12 please delete this post (blog) stop it please I haven't asked anyone to take it upon them selves to become my hit man.

All I do is come here on this forum & do my best & as everyone else does, there is no need for any kind of abuse or being disheartening, if any advice is incorrect there are others who will put it right no need to get upset about it.

Im fed up to the teeth seeing this, stop stop stop, if anyone cant contribute to a thread for what its meant for then just don't post anything but to make comments like this is not fitting in what we do here ...
With a small semblance of respect, using your alter ego and interjecting what you did here and then feigning disgust is sad behavior. The adult members here know this routine and it is unwanted. It is "hopeful" you won't do this again.

Since it didn't occur to you, I'll be the adult and apologize to Kongolo for the disruption in his thread.

Kongolo, sorry this happened and hopefully your issue will be addressed without any more sideshows. I will commit to sticking with you until you can get to the solution.
 
Old Nov 13, 2019 | 04:44 AM
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Originally Posted by Rico.Adams
Steve

Since you've replied from my post its seems you once again you are directing this to me "you won't do this again" let me tell you something from my side this has nothing to do with me nor did I ask W12 to get involved in my matters Im wise enough to tackle something that is directed to me.

You have something to say then direct it to the person it is intended as I have & if you don't want to do that & make a statement then make a fresh post, your constant digs at me in a way you seem to think I may not understand, makes me wonder why your on the forum, you many times mentioned to me in your PM's you were slowly moving out of this forum as your involved in another & that the forum was dead. You come across as if your the victim but all the PM's you've sent having digs at some of the other members how you disapprove the way they answer posts asking me for an opinion, yes Steve I still have those PM's, maybe I should list all the members you disapprove of & let the members see the real you.

Its you in a coordinated way of yours who's making the forum into a battle field, you didn't have to make this statement, W12 hasn't replied to my request, but once again you jump in make remarks to something that was NOT directed to you but to W12, as you can see I replied to W12's post.

I clearly stated in my post to stop this nonsense but oh NO Mr BWings has to flair it up again, can't leave it alone can you Steve, W12 hasn't replied as mentioned maybe he doesn't want to or he hasn't seen it, which ever the case may be let him answer if he ever does, in your post the one you answered to W12's you told W12 who made him the thread police, so what's make you the thread police by mentioning "hopefully you won't do it again".

I wasn't going to say anything & left it alone when I read it, but now you've flared this up, I ask you to explain your directed comment to me "Quit the game Rico. We know who you are!".
Please do explain ...

For a 69 year old man its shameful you behave in such a way ...
Shameful is a 54 year old man that cannot be trusted. PMs are just that. They represent exchanges between two individuals who are confident they can speak in a manner that is not intended for a public audience.

I realized, after I gave that trust to you it was a mistake the first time you came on a public site uttering words from those PMs. Now here you are doing more of it. This is the reason I will never trust you again and this is a stern warning to others. Just read Ricos words in this post. Hopefully you don't make the mistake I did.

And, if you want to start that kind of mud slinging, two can play. I'm sure everyone here would enjoy hearing how you've trashed each member by name, along with the constant whining you do about no one likes you anymore and no one wants you to be a member here.

As far as W12 goes - You are W12. We all know it. Stop the facade. Delete the account. No one here appreciates you having a public conversation with yourself, especially since you think you walk on water.
 
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